This invention relates to kilowatt-hour meters such as are provided by an electrical supply utility on a consumer's premises to measure electrical energy consumption.
The present invention is concerned more particularly with the detection of any tampering with the metering. It is the usual practice to seal the meter unit, e.g. with lead seals, so that it can readily be determined by visual inspection whether anyone has opened the meter unit. One common method of tampering with the meter is to put a wire link as a bypass across the unit. This link is put between the live lead on the utility side of the meter and a point on the live lead on the consumer side of the meter, commonly at the consumer's switch and fuse unit. The link bypasses the meter so that only about half the energy consumed is recorded by the meter; the other half passes through the bypass link. It is possible to take the further step of breaking the lead between the meter and the connection to the "illegal" link so that no current passes through the meter and thus no energy consumption is recorded. This further step is less common because such a break in the lead leaves visible evidence of tampering.